1. Field of the Invention
The present invention relates to the filtering of particulate matter from a slurry. More specifically, the present invention relates to the filtering of slurries having a relatively high particulate content utilizing a displacement filtering principle.
2. Description of the Related Art
Separating the liquid and solid components of a liquid-solid mixture, or slurry, is a necessary or desirable process in many industries. In many filtering applications, the slurry is a waste product and it is desirable to separate the solid and liquid matter and dispose of them separately. Often, the solid component may be a hazardous material and the liquid component may be reused or recycled. In other applications, the liquid component may be the final product, such as in the wine industry, for example. In this application, the solid component is desirably separated from the liquid to provide purity and clarity to the wine.
One method for separating liquids and solids is known as surface filtering. In a surface filtering process, the liquid-solid mixture is passed through a filter element under the influence of gravity or a relatively low pressure. The liquid component of the mixture passes through the filter element while the solid component is retained primarily on the surface of the filter element. However, with this type of filtering process, once the surface of the filter element is substantially covered with solid particulate matter, liquid is no longer able to pass through. Thus, surface filter processes are useful only for filtering slurries having a low concentration of solid matter.
A method more suitable for filtering slurries having a relatively high concentration of solids utilizes an apparatus referred to as a tube press. A tube press typically includes a cylindrical tube with a smaller diameter cylindrical filter concentrically positioned therein. A flexible bladder is positioned adjacent the inner surface of the tube. A fixed volume of slurry is introduced into a space between the tube and the inner filter and an inlet to the tube is closed and sealed. Hydraulic fluid is forced under pressure into a gap between the tube and the bladder to expand the bladder. The expansion of the bladder forces the liquid within the tube through the filter, while the solid matter is retained within the tube. However, this method of filtering is inefficient because the tube press only processes a fixed volume of slurry during a filtering cycle. As a result, the solid matter remaining at the end of the filter cycle is typically only a small percentage of the total available volume defined between the tube and the filter. Additionally, solids must be removed and the filter cleaned between each filtering cycle. Consequently, this process is typically used only in applications where the slurry has an extremely high concentration of solids or in applications where an extremely dry particulate xe2x80x9ccakexe2x80x9d is desired.
Another method of filtering slurries having relatively high concentrations of solid matter uses an apparatus known as a filter press, which operates under a displacement filtering principle. A filter press utilizes a series of filter plates placed adjacent to one another. A space is defined between each pair of the filter plates and each space is lined with filter media. Typically, each of the filter plates include a central aperture. Thus, all of the spaces between each pair of plates communicate with one another. An inlet is provided to introduce slurry into the interconnected spaces on an upstream side of the filter media. One or more outlets communicate with each space on a downstream side of the filter element.
Slurry is introduced through the inlet to fill all of the individual spaces between the filter plates. Once the spaces are filled, the delivery pressure of the incoming slurry is increased such that the liquid component is displaced through the filter media and the solid particulate matter is retained within the spaces upstream from the filter media. The filtered liquid, or filtrate, moves to the outlet(s), where it is discharged. The filter cycle continues until each of the spaces is substantially filled with particulate matter. Thus, the filter press utilizes substantially the entire volume of the spaces rather than relying on the surface area of the filter media, as is the case with surface filtering methods. However, due to the large forces generated by the pressure within the spaces, a large and costly support frame and hydraulic system is necessary to hold the plates together during the filter cycle. In addition, the solid particulate xe2x80x9ccakexe2x80x9d remaining in each individual space after the filter cycle must be removed in preparation for a subsequent filter cycle. Because as many as a hundred or more individual plates may be used, the cleaning process is very time-consuming and results in excessive down-time in which the filter press is not utilized. Also, due to the provision of multiple plates, which must be separated from one another to allow the particulate matter to be discharged and the filter media to be cleaned, fully automated filtering systems are often prohibitively expensive.
Advantageously, preferred embodiments and methods utilize a displacement principle for filtering slurries having a relatively high concentration of solids without the above-described disadvantages associated with the filter press. Preferred embodiments utilize a simplified structural arrangement to permit a less costly support structure and closure system to be provided. In addition, preferred embodiments drastically reduce the time necessary for discharging particulate matter and preparing the filter for subsequent use. Furthermore, preferred embodiments are desirably capable of being equipped with simplified and cost-effective automated cleaning systems to preferably completely eliminate the need for an operator and further reduce the down-time of the filter apparatus.
A preferred embodiment is a filter apparatus including a first outlet and a second outlet. The filter additionally includes an annular inner filter defining an external surface, an internal surface and an internal cavity. The first outlet is located downstream from the internal surface of the inner filter. An outer filter surrounds the inner filter and defines an internal surface and an external surface. The inner filter and the outer filter define an annular particulate collection volume. The second outlet is located downstream from the external surface of the outer filter. The filter includes an inlet directing fluid into the particulate collection volume before the fluid passes through either the inner filter or the outer filter. A pressure source is positioned upstream from the inlet and directs pressure through the inlet to force fluid within the particulate collection volume through the inner filter to the first outlet and through the outer filter to the second outlet.
A preferred embodiment is a filter apparatus for dewatering a slurry including a pressure vessel having a first end, a second end, and a one-piece, annular side wall portion. The side wall portion has an internal surface generally defining an internal space and one of the first end and the second end defines an opening to permit access to the internal space. A closure is sized and shaped for selectively closing the opening. The pressure vessel and the closure are configured to withstand a pressure of at least 25 psi in the internal space when the opening is closed. An annular inner filter defines an external surface and an internal cavity, the internal cavity at least partially defining a first outlet space. A substantial portion of the inner filter which forms the external surface includes a first filter media. An outer filter surrounds the inner filter and defines an internal surface facing the external surface. A substantial portion of the outer filter which forms the internal surface includes a second filter media. The first filter media and the second filter media comprise a woven material or a material configured to retain a particulate size greater than or equal to about 0.25 microns. The first and second filter media define an annular particulate collection volume between them. The outer filter and the internal surface of the vessel define a second outlet space between them. An inlet communicates with the internal space and is configured to direct a slurry into the particulate collection volume before the slurry passes through either the inner filter or the outer filter. An outlet communicates with the internal space and is in fluid communication with both the first outlet space and the second outlet space. A pressure source is upstream from the inlet and pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the inner filter to the first outlet space and through the outer filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake. The opening is sized and shaped to permit a particulate cake within the particulate collection volume to be removed through the opening.
A preferred embodiment is a filter apparatus for dewatering a slurry including a pressure vessel having a first end, a second end, and a one-piece, annular side wall portion. The side wall portion has an internal surface generally defining an internal space. Either the first end or the second end defines an opening to permit access to the internal space. A closure is sized and shaped for selectively closing the opening. An annular inner filter defines an external surface and an internal cavity, which at least partially defines a first outlet space. A substantial portion of the inner filter which forms the external surface includes a first filter media. An outer filter surrounds the inner filter and defines an internal surface facing the external surface. The internal surface and the external surface are substantially parallel and a substantial portion of the outer filter which forms the internal surface includes a second filter media. The first filter media and the second filter media comprise either a woven material or a material configured to retain a particulate size greater than or equal to about 0.25 microns. The first and second filter media define an annular particulate collection volume therebetween and the outer filter and the internal surface of the vessel define a second outlet space therebetween. An inlet communicates with the internal space and is configured to direct a slurry into the particulate collection volume before the slurry passes through either of the inner filter and the outer filter. An outlet communicates with the internal space and is in fluid communication with the first outlet space and the second outlet space. A pressure source is upstream from the inlet and pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the inner filter to the first outlet space and through the outer filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake. The opening is sized and shaped to permit a particulate cake within the particulate collection volume to be removed through the opening. The pressure source produces a first fluid pressure upstream from the particulate collection volume and a second fluid pressure downstream from the particulate collection volume. The difference between the first fluid pressure and the second fluid pressure define a pressure differential. The filter apparatus is configured to withstand operating pressure differentials of at least 25 psi.
A preferred embodiment is a filter apparatus for filtering a slurry including a pressure vessel having a first end, a second end and an annular wall. A support portion is configured to secure the pressure vessel in a location. The wall of the pressure vessel includes a first portion between the support and the first end or the second end of the vessel. The first portion of the wall is capable of providing sufficient resistance to gravity acting on the first portion of the wall to maintain the structural integrity of the first portion of the wall. An annular inner filter defines an external surface and an internal cavity, which at least partially defines a first outlet space. A substantial portion of the inner filter which forms the external surface includes a first filter media. An outer filter surrounds the inner filter and defines an internal surface facing the external surface. A substantial portion of the outer filter which forms the internal surface includes a second filter media. The first filter media and the second filter media comprise either a woven material or a material configured to retain a particulate size greater than or equal to about 0.25 microns. The first and second filter media define an annular particulate collection volume therebetween and the outer filter and the internal surface of the vessel defining a second outlet space therebetween. An inlet communicates with the internal space and directs the slurry into the particulate collection volume before passing through either of the inner filter and the outer filter. An outlet communicates with the internal space and is in fluid communication with the first outlet space and the second outlet space. A pressure source is upstream from the inlet and pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the inner filter to the first outlet space and through the outer filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake.
A preferred embodiment is a filter apparatus as recited in the preceding paragraph and additionally comprising a second support portion configured to secure the pressure vessel in a location. The wall of the pressure vessel including a second portion between the first support and the second support. The second portion of the wall being capable of providing sufficient resistance to gravity acting on the second portion of the wall to maintain the structural integrity of the second portion of the wall. A preferred embodiment is a filter apparatus as in the preceding paragraph, wherein the inner filter and the outer filter comprise a filter assembly having a first end and a second. The filter apparatus further comprising a first filter assembly support and a second filter assembly support. The filter assembly includes a portion between the first filter assembly support and the second filter assembly support. The portion of the filter assembly being capable of providing sufficient resistance to gravity acting on the filter assembly to maintain the structural integrity of the filter assembly.
A preferred embodiment is a filter apparatus for dewatering a slurry, including a pressure vessel having a first end, a second end, and a one-piece, annular side wall portion. The side wall portion has an internal surface generally defining an internal space. One of the first end and the second end defines an opening to permit access to the internal space and a closure is sized and shaped for selectively closing the opening. The pressure vessel and the closure are configured to withstand a pressure of at least 25 psi in the internal space when the opening is closed. The apparatus includes at least one filter assembly comprising a first filter and a second filter. The first filter defines a first surface and at least partially defines a first outlet space. A substantial portion of the first filter which forms the first surface comprises a first filter media. The second filter defines a second surface facing the first surface and at least partially defines a second outlet space. A substantial portion of the second filter which forms the second surface comprises a second filter media. The first and second filter media define a particulate collection volume therebetween. An inlet communicates with the internal space and is configured to direct a slurry into the particulate collection volume before passing through either of the first filter and the second filter. An outlet communicates with the internal space and is in fluid communication with the first outlet space and the second outlet space. A pressure source is disposed upstream from the inlet, wherein pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the first filter to the first outlet space and through the second filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake. The opening is sized and shaped to permit a particulate cake within the particulate collection volume to be removed through the opening. The apparatus also includes a scraper sized and shaped to extend substantially from the first filter media to the second filter media. The scraper is movable from a first end of the particulate collection volume toward a second end of the particulate collection volume to remove particulate cake from the particulate collection volume.
A preferred embodiment is a filter apparatus for dewatering a slurry, comprising a pressure vessel having a first end, a second end, and a one-piece, annular side wall portion. The side wall portion has an internal surface generally defining an internal space. One of the first end and the second end define an opening to permit access to the internal space. A closure is sized and shaped for selectively closing the opening. The apparatus includes at least one filter assembly comprising a first filter and a second filter. The first filter define a first surface and at least partially defines a first outlet space. A substantial portion of the first filter which forms the first surface comprises a first filter media. The second filter defines a second surface facing the first surface and at least partially defines a second outlet space. The first surface and the second surface are substantially parallel and a substantial portion of the second filter which forms the second surface comprises a second filter media. The first and second filter media define a particulate collection volume therebetween. An inlet communicates with the internal space and is configured to direct a slurry into the particulate collection volume before passing through either of the first filter and the second filter. An outlet communicates with the internal space and is in fluid communication with the first outlet space and the second outlet space. A pressure source is disposed upstream from the inlet, wherein pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the first filter to the first outlet space and through the second filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake. The opening is sized and shaped to permit a particulate cake within the particulate collection volume to be removed through the opening. The pressure source produces a first fluid pressure upstream from the particulate collection volume and a second fluid pressure downstream from the particulate collection volume. The difference between the first fluid pressure and the second fluid pressure defines a pressure differential. The filter apparatus is configured to withstand operating pressure differentials of at least 25 psi. The apparatus also includes a scraper sized and shaped to extend substantially from the first filter media to the second filter media, the scraper being movable from a first end of the particulate collection volume toward a second end of the particulate collection volume to remove particulate cake from the particulate collection volume.
A preferred embodiment is a filter apparatus for filtering a slurry, comprising a pressure vessel having a first end, a second end and an annular wall. A support portion is configured to secure the pressure vessel in a location. The wall of the pressure vessel includes a first portion between the support and one of the first end and the second end of the vessel, which is capable of providing sufficient resistance to gravity acting on the first portion of the wall to maintain the structural integrity of the first portion of the wall. The apparatus includes at least one filter assembly having a first filter and a second filter. The first filter defines a first surface and at least partially defines a first outlet space. A substantial portion of the first filter which forms the first surface comprises a first filter media. The second filter defines a second surface facing the first surface and at least partially defines a second outlet space. A substantial portion of the second filter which forms the second surface comprises a second filter media, the first and second filter media defining a particulate collection volume therebetween. An inlet communicates with the internal space and directs the slurry into the particulate collection volume before the slurry passes through either of the first filter or second filter. An outlet communicates with the internal space and is in fluid communication with the first outlet space and the second outlet space. A pressure source is disposed upstream from the inlet, wherein pressure from the pressure source is directable through the inlet to force a fluid component of a slurry within the particulate collection volume through the first filter to the first outlet space and through the second filter to the second outlet space. The first and second filter media retain a solid component of a slurry within the particulate collection volume to form a particulate cake. A scraper is sized and shaped to extend substantially from the first filter media to the second filter media. The scraper is movable from a first end of the particulate collection volume toward a second end of the particulate collection volume to remove particulate cake from the particulate collection volume.
A preferred method of separating particulate matter from a slurry includes providing a first outlet and providing a particulate collection volume. The method additionally includes providing a first annular filter separating the first outlet from the particulate collection volume. A flow of the slurry is directed into the particulate collection volume under sufficient pressure to force fluid through the first annular filter and any of the particulate matter blocking a filtering surface of the first annular filter to substantially fill the particulate collection volume with particulate.
A preferred embodiment is a filter apparatus including a pressure vessel defining an interior space. The filter apparatus includes a first filter defining a first surface and a second filter defining a second surface. The second surface faces the first surface. The first filter and the second filter at least partially define a particulate collection volume therebetween. An inlet directs fluid into the particulate collection volume before the fluid passes through either the first filter or the second filter. At least one outlet is located downstream from at least one of the first surface and the second surface. A pressure source is positioned upstream from the inlet and directs pressure through the inlet to force fluid within the collection volume through the first filter and the second filter to the at least one outlet.
A preferred embodiment is a filter apparatus having an annular inner filter defining an internal cavity and an outer filter surrounding the inner filter. The inner filter and the outer filter define an annular particulate collection volume when the filter apparatus is in a closed position. The inner filter and the outer filter are movable axially with respect to one another to define an open position wherein particulate may be emptied from the filter apparatus. The filter includes an inlet and an outlet. The outlet is located downstream from the particulate collection volume and the inlet directs fluid into the particulate collection volume before the fluid passes through either the inner filter or the outer filter. The filter also includes a drive having a portion which exerts force on at least one of the inner filter and the outer filter to move the filter apparatus between the open position and the closed position.
A preferred embodiment is a method of separating particulate matter from a slurry including providing a filter apparatus comprising an annular inner filter and an outer filter surrounding the inner filter. The inner filter and the outer filter define an annular particulate collection volume between them. The filter apparatus further includes an outlet located downstream from the particulate collection volume and an inlet directing fluid into the particulate collection volume before the fluid passes through either the inner filter or the outer filter. The method further includes initiating a filtering cycle comprising directing a flow of the slurry into the particulate collection volume under sufficient pressure to force fluid through the inner and outer filters and any of the particulate matter blocking a filtering surface of the inner and outer filters to substantially fill the particulate collection volume and initiating a drive to move the inner filter and the outer filter axially with respect to one another upon completion of the filtering cycle to empty particulate from the particulate collection volume.
A preferred embodiment is a filter apparatus including an annular inner filter defining an internal cavity and an outer filter surrounding the inner filter. The inner filter and the outer filter define an annular particulate collection volume when the filter apparatus is in a closed position. The inner filter and the outer filter are movable axially with respect to one another to define an open position wherein particulate may be emptied from the filter apparatus. An outlet is located downstream from the particulate collection volume and an inlet directs fluid into the particulate collection volume before the fluid passes through either the inner filter or the outer filter. The filter includes means for moving the filter apparatus between the open position and the closed position.